To evaluate the performance of our method on real data, we select multi-track songs that contain realistic violin and piano stems from the MedleyDB [1]}, [2]} for evaluation. There are only 16 such songs, highlighting the difficulty of collecting multi-track recordings for model training. Moreover, after listening to these songs one-by-one, we discard 10 of them, as there are severe leakage issues and accordingly the piano/violin stems are not purely piano/violin. We also note that most of the remaining six songs contain more than one violin stems. For such songs, we consider the combination of the piano track and one of the violin tracks as the input mixture, thereby creating multiple partially realistic mixtures from the same song. All the other instruments from these songs (e.g., cello) are also excluded. As a result, we have 16 violin piano ensembles in total for evaluation.
